Note 1 - Summary of Significant Accounting Policies (Details Textual) $ in Thousands				3 Months Ended	12 Months Ended
		Oct. 01, 2021 USD ($)	Jun. 24, 2021	Sep. 25, 2021	Dec. 25, 2021 USD ($) shares	Dec. 26, 2020 USD ($) shares	Dec. 28, 2019 USD ($) shares
Gain (Loss) on Disposition of Business	[1]				$ 70,815	$ (0)	$ (0)
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares) | shares					180,000	113,000	422,000
SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Cost and Expense					$ 7,100	$ 8,100	$ 4,800
Gain (Loss) on Disposition of Property Plant Equipment, Total					(0)	4,495	(0)
Depreciation, Total					13,200	14,000	19,300
Capitalized Computer Software, Gross					13,500	13,500
Capitalized Computer Software, Amortization					$ 1,644	1,191	0
Number of Operating Segments					3
Number of Reportable Segments			2	1	1
Goodwill and Intangible Asset Impairment, Total		$ 0
Revenue, Remaining Performance Obligation, Amount					$ 7,700	8,300
Provision for Doubtful Accounts					0
Contract with Customer, Asset, after Allowance for Credit Loss, Total					0
Contract with Customer, Liability, Total					21,900	17,100
Deferred Profit					13,208	8,671
Deferred Profit Long-term					6,100	6,700
Amortization of Debt Issuance Costs					600	1,200	1,100
Accumulated Other Comprehensive Income (Loss), Net of Tax, Total					(27,262)	(4,326)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax					(23,000)	27,300
Foreign Currency Transaction Gain (Loss), Realized					$ 400	(3,200)
Computer Software, Intangible Asset [Member]
Finite-Lived Intangible Asset, Useful Life (Year)					7 years
Minimum [Member]
Standard Product Warranty Term (Month)					12 months
Maximum [Member]
Standard Product Warranty Term (Month)					36 months
Building [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)					30 years
Building [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)					40 years
Building Improvements [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)					5 years
Building Improvements [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)					15 years
Machinery, Equipment and Software [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)					3 years
Machinery, Equipment and Software [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)					10 years
Xcerra [Member]
Inventory Write-down						$ 2,100	$ 700
ALBS [Member]
Variable Interest Entity, Ownership Percentage Sold							20.00%
Gain (Loss) on Disposition of Business							$ 100

[1] On June 24, 2021 we completed the divestment of our PCB Test business. The divestment of this business did not qualify for presentation as discontinued operations and the results of the PCB Test business are included in continuing operations for all periods presented. See Note 14, “Business Divestitures and Discontinued Operations” for additional information on this transaction and financial statement presentation.